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<title>GDB&rsquo;s Obsolete Annotations: Value Annotations</title>

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<a name="Value-Annotations"></a>
<div class="header">
<p>
Next: <a href="Frame-Annotations.html#Frame-Annotations" accesskey="n" rel="next">Frame Annotations</a>, Previous: <a href="Server-Prefix.html#Server-Prefix" accesskey="p" rel="prev">Server Prefix</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
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<hr>
<a name="Values"></a>
<h2 class="chapter">5 Values</h2>

<p><em>Value Annotations have been removed.  <small>GDB/MI</small> instead provides
Variable Objects.</em>
</p>
<a name="index-annotations-for-values"></a>
<p>When a value is printed in various contexts, <small>GDB</small> uses
annotations to delimit the value from the surrounding text.
</p>
<a name="index-value_002dhistory_002dbegin"></a>
<a name="index-value_002dhistory_002dvalue"></a>
<a name="index-value_002dhistory_002dend"></a>
<p>If a value is printed using <code>print</code> and added to the value history,
the annotation looks like
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zvalue-history-begin <var>history-number</var> <var>value-flags</var>
<var>history-string</var>
^Z^Zvalue-history-value
<var>the-value</var>
^Z^Zvalue-history-end
</pre></div>

<p>where <var>history-number</var> is the number it is getting in the value
history, <var>history-string</var> is a string, such as &lsquo;<samp>$5 = </samp>&rsquo;, which
introduces the value to the user, <var>the-value</var> is the output
corresponding to the value itself, and <var>value-flags</var> is &lsquo;<samp>*</samp>&rsquo; for
a value which can be dereferenced and &lsquo;<samp>-</samp>&rsquo; for a value which cannot.
</p>
<a name="index-value_002dbegin"></a>
<a name="index-value_002dend"></a>
<p>If the value is not added to the value history (it is an invalid float
or it is printed with the <code>output</code> command), the annotation is similar:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zvalue-begin <var>value-flags</var>
<var>the-value</var>
^Z^Zvalue-end
</pre></div>

<a name="index-arg_002dbegin"></a>
<a name="index-arg_002dname_002dend"></a>
<a name="index-arg_002dvalue"></a>
<a name="index-arg_002dend"></a>
<p>When <small>GDB</small> prints an argument to a function (for example, in the output
from the <code>backtrace</code> command), it annotates it as follows:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zarg-begin
<var>argument-name</var>
^Z^Zarg-name-end
<var>separator-string</var>
^Z^Zarg-value <var>value-flags</var>
<var>the-value</var>
^Z^Zarg-end
</pre></div>

<p>where <var>argument-name</var> is the name of the argument,
<var>separator-string</var> is text which separates the name from the value
for the user&rsquo;s benefit (such as &lsquo;<samp>=</samp>&rsquo;), and <var>value-flags</var> and
<var>the-value</var> have the same meanings as in a
<code>value-history-begin</code> annotation.
</p>
<a name="index-field_002dbegin"></a>
<a name="index-field_002dname_002dend"></a>
<a name="index-field_002dvalue"></a>
<a name="index-field_002dend"></a>
<p>When printing a structure, <small>GDB</small> annotates it as follows:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zfield-begin <var>value-flags</var>
<var>field-name</var>
^Z^Zfield-name-end
<var>separator-string</var>
^Z^Zfield-value
<var>the-value</var>
^Z^Zfield-end
</pre></div>

<p>where <var>field-name</var> is the name of the field, <var>separator-string</var>
is text which separates the name from the value for the user&rsquo;s benefit
(such as &lsquo;<samp>=</samp>&rsquo;), and <var>value-flags</var> and <var>the-value</var> have the
same meanings as in a <code>value-history-begin</code> annotation.
</p>
<p>When printing an array, <small>GDB</small> annotates it as follows:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zarray-section-begin <var>array-index</var> <var>value-flags</var>
</pre></div>

<p>where <var>array-index</var> is the index of the first element being
annotated and <var>value-flags</var> has the same meaning as in a
<code>value-history-begin</code> annotation.  This is followed by any number
of elements, where is element can be either a single element:
</p>
<a name="index-elt"></a>
<div class="smallexample">
<pre class="smallexample">&lsquo;<samp>,</samp>&rsquo; <var>whitespace</var>         ; <span class="roman">omitted for the first element</span>
<var>the-value</var>
^Z^Zelt
</pre></div>

<p>or a repeated element
</p>
<a name="index-elt_002drep"></a>
<a name="index-elt_002drep_002dend"></a>
<div class="smallexample">
<pre class="smallexample">&lsquo;<samp>,</samp>&rsquo; <var>whitespace</var>         ; <span class="roman">omitted for the first element</span>
<var>the-value</var>
^Z^Zelt-rep <var>number-of-repetitions</var>
<var>repetition-string</var>
^Z^Zelt-rep-end
</pre></div>

<p>In both cases, <var>the-value</var> is the output for the value of the
element and <var>whitespace</var> can contain spaces, tabs, and newlines.  In
the repeated case, <var>number-of-repetitions</var> is the number of
consecutive array elements which contain that value, and
<var>repetition-string</var> is a string which is designed to convey to the
user that repetition is being depicted.
</p>
<a name="index-array_002dsection_002dend"></a>
<p>Once all the array elements have been output, the array annotation is
ended with
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zarray-section-end
</pre></div>

<hr>
<div class="header">
<p>
Next: <a href="Frame-Annotations.html#Frame-Annotations" accesskey="n" rel="next">Frame Annotations</a>, Previous: <a href="Server-Prefix.html#Server-Prefix" accesskey="p" rel="prev">Server Prefix</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
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